Liquid crystal composition containing 2-methyl-3,4,5-trifluorobenzene liquid crystal compound and application thereof

ABSTRACT

The present invention relates to the technical field of liquid crystal displays, and particularly relates to a liquid crystal composition containing a 2-methyl-3,4,5-trifluorobenzene liquid crystal compound and use thereof, wherein the liquid crystal composition of the present invention comprises, in percentages by weight, 1-50% of one or more compounds represented by general formula I and 10-70% of one or more compounds represented by general formula II, and may further comprise 0-30% of compounds represented by general formula III and/or 6-45% of one or more compounds represented by general formulas IV to XIII The liquid crystal composition provided by the present invention has a low rotational viscosity and a large elastic constant, is presented as having a shorter response time, and can significantly improve the display effect of a liquid crystal display when applied to TN, IPS and FFS mode displays.

FIELD OF THE INVENTION

The present invention relates to the technical field of liquid crystal displays, and particularly relates to a liquid crystal composition containing a 2-methyl-3,4,5-trifluorobenzene liquid crystal compound and use thereof. In particular, the present invention provides a liquid crystal composition containing a liquid crystal compound in which 2-methyl-3,4,5-trifluorobenzene is linked to a difluoromethoxy bridge bond. The liquid crystal composition provided by the present invention has a fast response time, and is particularly suitable for TN/IPS/FFS-type liquid crystal display devices.

BACKGROUND OF THE INVENTION

Currently, liquid crystal has been widely applied in the information display field, and has also made some progress in optical communication applications (S. T. Wu, D. K. Yang. Reflective Liquid Crystal Displays. Wiley, 2001). In recent years, the application field of liquid crystal compounds has been significantly broadened to various types of display devices, electro-optical devices, electronic components, sensorsand the like. Nematic liquid crystal compounds have been most widely used in flat panel displays, particularly in TFT active matrix systems.

Liquid crystal display has gone through a long path of development since the discovery of liquid crystals. In 1888, Friedrich Reinitzer, an Austrian botanist, discovered the first liquid crystal material, i.e., cholesteryl benzoate. Manguin invented a rubbing orientation method for producing a single domain liquid crystal and studying optical anisotropy in 1917. E. Bose established Swarm doctrine in 1909, which was supported by experiments of L. S. Ormstein and F. Zernike et al. (1918), and was later explained as statistical fluctuations by De Gennes. In 1933, G W. Oseen and H. Zocher founded continuum theory which was modified by F. C. Frank (1958). M. Born (1916) and K. Lichtennecker (1926) found and studied liquid crystal dielectric anisotropy. In 1932, W. Kast accordingly divided the nematic phase into two categories: positive and negative. In 1927, V. Freedericksz and V. Zolinao discovered that nematic liquid crystal would be deformed and present a voltage threshold (Freederichsz change) in an electric field or magnetic field. This discovery provides a basis for the fabrication of liquid crystal displays.

In 1968, R. Williams in Radio Corporation of America (RCA) found that nematic phase liquid crystals formed stripe domains and had a light scattering phenomenon in an electric field. G H. Heilmeir then developed this into a dynamic scattering display mode, and made the first liquid crystal display (LCD) in the world. In the early 1970s, Helfrich and Schadt invented twisted-nematic (TN) principle. The combination of the TN photoelectric effect and integrated circuit made a display device (TN-LCD), which has opened up a broad application prospect for liquid crystals. Particularly since the seventies, due to the development of large-scale integrated circuits and liquid crystal materials, the application of liquid crystals has made a breakthrough development in terms of display. Super Twisted Nematic (STN) mode proposed successively by T. Scheffer et al. in 1983-1985 and an Active Matrix (AM) mode proposed by P. Brody in 1972 were re-adopted. Conventional TN-LCD technology has been developed into STN-LCD and TFT-LCD technologies. Although the number of STN scanning lines can reach 768 or greater, there are still problems, such as response speed, viewing angle and gray scale, when the temperature rises. Therefore, for a large area, high information content, color display, an active matrix display mode becomes the first choice. TFT-LCD has been widely used in direct-view televisions, large-screen projection televisions, computer terminal displays and certain military instrument displays. It is believed that TFT-LCD technology will have broader application prospects.

There are two types of “active matrix” including: 1. a metal oxide semiconductor (MOS) on a silicon wafer as a substrate; and 2. a thin film transistor (TFT) on a glass plate as a substrate.

Monocrystalline silicon as a substrate material limits the display size due to the fact that there were many problems occurring at junctions of each part of a display device or even a module assembly. Accordingly, the second type of thin film transistor is a promising active matrix type. The photoelectric effect utilized is generally the TN effect. A TFT includes a compound semiconductor, such as CdSe, or a TFT based on polycrystalline silicon or amorphous silicon.

Currently, the LCD product technologies have been well established and successfully solved technical problems regarding viewing angle, resolution, color saturation, brightness, etc., and the display performance thereof has been close to or superior to that of CRT displays. Large-size and small-to-medium-size LCDs have gradually dominated the flat panel displays in respective fields. However, due to the limitation of (the high viscosity of) the liquid crystal material itself, the response time becomes a principal factor affecting high-performance displays.

In particular, the response time of a liquid crystal is limited by the rotational viscosity y1 and the elastic constant of the liquid crystal. Therefore, reducing the rotational viscosity of a liquid crystal composition and increasing the elastic constant have a significant effect on reducing the response time of the liquid crystal display and accelerating the response speed of the liquid crystal display.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a liquid crystal composition and use thereof.

In order to achieve the above object, the following technical solution is specifically adopted:

a liquid crystal composition containing a 2-methyl-3,4,5-trifluorobenzene liquid crystal compound, comprising, in percentages by weight, 1-50% of one or more compounds represented by general formula I and 10-70% of one or more compounds represented by general formula II,

wherein R₁, R₂ and R₃ each independently represent a C₁-C₁₂ linear alkyl group or a C₁-C₁₂ linear alkyl group having one or more non-adjacent CH₂ substituted with O, S or CH═CH;

n each independently represents 0 or 1;

A₁, A₂ and A₃ each independently represent the following structures:

and

A₄ and A₅ each independently represent a trans-1,4-cyclohexylene group or a 1,4-phenylene group.

The liquid crystal composition provided by the present invention has a low rotational viscosity and a large elastic constant, and is presented as having a shorter response time, so that the problem of the slow response of the liquid crystal display is effectively solved.

In order to achieve a fast response time, the liquid crystal composition of the present invention comprises, in percentages by weight, 3-20% of one or more compounds represented by general formula I, and 17-63% of one or more compounds represented by general formula II; or comprises 21-45% of one or more compounds represented by general formula I, and 20-45% of one or more compounds represented by general formula II.

The liquid crystal composition of the present invention further comprises 0-30% by weight of one or more compounds represented by general formula III, and preferably further comprises 2-30% by weight of one or more compounds represented by general formula III,

wherein R₄ and R₅ each independently represent a C₁-C₁₂ linear alkyl group or a C₁-C₁₂ linear alkyl group having one or more non-adjacent CH₂ substituted with O, S or CH═CH; and

A₆ each independently represents the following structures:

As a preferred technical solution of the present invention, the amount of one or more compounds represented by general formula III is 2-26% by weight.

The liquid crystal composition of the present invention further comprises 6-45% by weight of one or more compounds represented by general formulas IV to IX,

wherein R₆ and R₉ each independently represent a C₁-C₁₂ linear alkyl group or a C₁-C₁₂ linear alkyl group having one or more non-adjacent CH₂ substituted with CH═CH; R₇, R₈ and R₁₀-R₁₂ each independently represent a C₁-C₁₂ linear alkyl group; L₁-L₈ each independently represent H or F; and X₁—X₃ and X₅ each independently represent F, CF₃, OCF₂H or OCF₃; X₄ each independently represents F, CF₃, OCF₃, and a C₁-C₅ linear alkyl group or a C₂-C₅ linear alkenyl group; and A₇ and A₈ are each independently selected from the following structures:

As a preferred technical solution of the present invention, the amount of one or more compounds represented by general formulas IV to IX is 28-37% by weight.

As an embodiment of the technical solution of the present invention, the liquid crystal composition of the present invention comprises, in percentages by weight, 6-39% of one or more compounds represented by general formula I,

22-62% of one or more compounds represented by general formula II,

2-26% of one or more compounds represented by general formula III, and

6-44% of one or more compounds represented by general formulas IV to IX.

Particularly, the compound represented by general formula I is selected from one or more of the compounds represented by formulas I-A to I-U:

The compound represented by general formula II is selected from one or more of the following compounds:

wherein R₁ each independently represents a C₁-C₇ linear alkyl group; R₂ each independently represents a C₁-C₇ linear alkyl group or linear alkoxy group or a C₂-C₇ linear alkenyl group; and R₃ each independently represents a C₁-C₇ linear alkyl group.

More particularly, the compound represented by general formula I is selected from one or more of the compounds represented by formulas I-A-1 to I-U-4:

The compound represented by general formula II is selected from one or more of the compounds represented by formulas II-A-1 to II-C-24:

Particularly, the compound represented by general formula III is selected from one or more of the following compounds of formulas III-A to III-C:

wherein R₄ each independently represents a C₂-C₁₀ linear alkyl group or linear alkenyl group; and R₅ each independently represents a C₁-C₈ linear alkyl group.

More preferably, the compound represented by general formula III is selected from one or more of the structures of formulas III-A-1 to III-C-30:

In particular, the compounds of general formulas IV to IX are selected from one or more of the following structures:

wherein R₆ each independently represents a C₂-C₇ linear alkyl group or linear alkenyl group; R₇, R₈ and R₁₀-R₁₂ each independently represent a C₂-C₇ linear alkyl group; R₉ and R_(x) each independently represent a C₁-C₇ linear alkyl group or a C₂-C₇ linear alkenyl group.

More preferably, R₆ each independently represents a C₂-C₅ linear alkyl group or linear alkenyl group; R₇, R₈ and R₁₀-R₁₂ each independently represent a C₂-C₅ linear alkyl group; and R₉ and R_(x) each independently represent a C₁-C₅ linear alkyl group or a C₂-C₅ linear alkenyl group.

The compound represented by general formula I in the liquid crystal composition provided by the present invention is a compound containing 2-methyl-3,4,5-trifluorobenzene linked to a difluoromethoxy bridge bond, wherein such compounds have a strong polarity and good mutual solubility characteristics, and the mutual solubility characteristics of such compounds can be effectively improved after the introduction of methyl in the second position, and surprisingly, as compared with methyl-free compounds, the compounds of type I provided by the present invention have a mutual solubility with an improvement of 30% or greater, and are more advantageous for improving the low temperature mutual solubility characteristics of the mixed liquid crystal; the compound represented by general formula II has a bicyclic structure and a low rotational viscosity and excellent mutual solubility characteristics, and is an essential component for a fast-response liquid crystal display; the compound represented by general formula III is a non-polar compound which has a high clearing point and a large elastic constant, and contributes to improving the elastic constant of the liquid crystal composition; and the compounds represented by general formulas IV to IX are mainly used for adjusting the clearing point and parameters, such as the optical anisotropy, of the liquid crystal composition.

The method for producing the liquid crystal composition of the present invention is not particularly limited, and the liquid crystal composition may be produced by mixing two or more compounds using a conventional method, e.g., being prepared by a method of mixing and dissolving various components at a high temperature, wherein the liquid crystal composition is dissolved in a solvent used for the compounds and mixed, and then the solvent is distilled off under a reduced pressure; or the liquid crystal composition of the present invention may be prepared according to a conventional method, e.g., being obtained by dissolving components with lower contents therein into main components with higher contents at a higher temperature, or dissolving the various components in an organic solvent, such as acetone, chloroform or methanol, and then mixing the solution, followed by the removal of the solvent.

The liquid crystal composition of the present invention has a low rotational viscosity, a large elastic constant, a good low temperature mutual solubility and a fast response speed, and can be used for fast-response liquid crystal display in a variety of display modes, and the use thereof in TN, IPS or FFS mode displays can significantly improve the display effect of liquid crystal displays.

Specific Embodiments

The following examples are intended to illustrate the invention, but not to limit the scope of the invention.

Unless otherwise indicated, the percentage in the present invention is weight percentage; the temperature unit is degrees Celsius; An represents optical anisotropy (at 25° C.); Ac represents dielectric anisotropy (at 25° C., 1000 Hz); V₁₀ represents voltage threshold, and is the characteristic voltage (V, at 25° C.) when the relative transmittance is changed by 10%; yl represents rotational viscosity (mPa·S, at 25° C.); Cp represents the clearing point (° C.) of the liquid crystal composition; and K₁₁, K₂₂ and K₃₃ represent splay, twist and bend elastic constants (pN, at 25° C.), respectively.

In each of the following examples, the group structures in the liquid crystal compound are represented by the codes shown in Table 1.

TABLE 1 Group structure codes of the liquid crystal compound Groups Codes Group names

C 1,4-cyclohexylene

P 1,4-phenylene

G 2-fluoro-1,4-phenylene

U 2,6-difluoro-1,4-phenylene

K 2-methyl-3,5-difluoro-1,4-phenylene —O— O Oxygen substituent —F F Fluorine substituent —CF₃ CF₃ Trifluoromethyl C_(n)H_(2n+1) or C_(m)H_(2m+1) n or m Alkyl group —CF₂O— Q Difluoromethoxy bridge bond —OCF₂H OCF₂H Difluoromethoxy

A 2,5-tetrahydropyran

D 2,6-dioxo-1,4-dioxane —(CH₂)_(n)— n Alkylene —C≡C— T Acetylenic bond —HC═CH— V Alkenyl

Taking the following compound structures as an example:

is represented as 4CDUQKF

is represented as 5CCPUF

In each of the following examples, the liquid crystal compositions are all prepared by a thermal dissolution method, comprising the following steps of: weighing liquid crystal compounds in percentage by weight using a balance, wherein the order of weighing and addition is not particularly specified, and usually, the weighing and mixing are carried out successively in order of the melting points of the liquid crystal compounds from high to low; heating and stirring same at 60-100° C. so that each component is melted uniformly; then subjecting same to filtration and rotary evaporation; and finally performing encapsulation to obtain a target sample.

In each of the following examples, the weight percentage of each component in the liquid crystal composition and the performance parameters of the liquid crystal composition are shown in the following tables.

EXAMPLE 1

TABLE 2 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 2APUQKF 5 Δn 0.098 I 3PGUQKF 6 Δε +2.6 II 3CCV1 12 Cp 81 II 1PP2V1 7 γ1 50 II 3CCV 43 K₁₁ 13.9 III VCCP1 11 K₂₂ 7.0 III V2CCP1 9.5 K₃₃ 15.6 VII 2PGP3 6 IX 3PPGUF 0.5

EXAMPLE 2

TABLE 3 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3CPPQKF 3 Δn 0.122 II 3CCV 51 Δε +2.3 II 3CCV1 7 Cp 75 VI 3PGUF 11 γ1 46 VII 1PGP2V 7 K₁₁ 12.2 VII 2PGP2V 8 K₂₂ 6.1 VII V2PGP1 13 K₃₃ 14.0

EXAMPLE 3

TABLE 4 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 2APUQKF 5 Δn 0.098 I 3PGUQKF 5 Δε +2.6 II 3CCV 43 Cp 81 II 3CCV1 12 γ1 49 II 1PP2V1 7 K₁₁ 13.8 III VCCP1 11 K₂₂ 6.9 III V2CCP1 9 K₃₃ 16.2 VII 2PGPF 6 IX 3PPGUF 2

EXAMPLE 4

TABLE 5 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3CPPQKF 6 Δn 0.117 II 3CCV 40 Δε +5.2 II 5PP1 7 Cp 81 III VCCP1 6 γ1 48 III 3CCP1 5 K₁₁ 12.8 IV 3CCPOCF₃ 5 K₂₂ 6.3 V 2CGUF 4 K₃₃ 13.6 V 3CPGF 6 VI 2PGUF 10 VII 2PGPF 7 IX 3CCPUF 4

EXAMPLE 5

TABLE 6 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 4DGUQKF 2 Δn 0.101 I 3CPPQKF 9 Δε +5.8 I 3CPUQKF 5 Cp 91 I 3PUQKF 11 γ1 62 II 3CC2V1 4 K₁₁ 13.8 II 3CCV1 5 K₂₂ 6.9 II 3CCV 35 K₃₃ 17.1 III VCPP3 8 III V2CCP1 10 III VCCP1 11

EXAMPLE 6

TABLE 7 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3CCQKF 19 Δn 0.098 II 5CCV 13 Δε +9.4 II 3CCV1 4 Cp 101 IV 2CCUF 8 γ1 111 IV 3CCUF 8 K₁₁ 11.0 IV 2CCGF 3 K₂₂ 5.5 IV 3CCGF 3 K₃₃ 15.7 IV 5CCGF 3 V 3CPUF 23 IX 2CCPUF 4 IX 3CCPUF 4 IX 4CCPUF 4 IX 5CCPUF 4

EXAMPLE 7

TABLE 8 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3CUQKF 7 Δn 0.116 I 3PUQKF 17 Δε +9.0 II 3CCV 22 Cp 90 III VCCP1 10 γ1 95 III V2CCP1 7 K₁₁ 12.8 IV 3CCPOCF₃ 5 K₂₂ 6.4 V 3CPUF 10 K₃₃ 16.5 VII 2PGP3 6 IX 2CCPUF 4 IX 3CCPUF 5 IX 4CCPUF 4 IX 3CCGUF 3

EXAMPLE 8

TABLE 9 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3PUQKF 16 Δn 0.116 II 3CCV1 8 Δε +9.0 II 5CCV 14 Cp 94 IV VCCGF 5 γ1 105 IV 3CCUOCF₂H 10 K₁₁ 13.0 IV 3CCPOCF₃ 5 K₂₂ 6.5 IV 5CCPOCF₃ 5 K₃₃ 16.6 V 3CPUF 15 VII 2PGPF 5 VII 2PGP3 3 VIII 3CPPC3 4 IX 3CCGUF 5 IX 3CCPUF 5

EXAMPLE 9

TABLE 10 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3PGUQKF 2 Δn 0.111 I 4PGUQKF 8 Δε +7.5 I 3PUQKF 12 Cp 75 II 3CCV 45 γ1 45 IV 3CCUF 10 K₁₁ 10.5 VII 2PGP3 10 K₂₂ 5.3 VII 2PGP4 4 K₃₃ 13.0 IX 2CCPUF 3 IX 3CCPUF 3 IX 4CCPUF 3

EXAMPLE 10

TABLE 11 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3APUQKF 14 Δn 0.096 I 3CCQKF 13 Δε +12.5 I 3PUQKF 12 Cp 90 II 3CCV 24 γ1 76 III VCCP1 9 K₁₁ 11.0 IV 2CCUF 5 K₂₂ 5.5 IV 3CCUF 10 K₃₃ 13.6 IV 3CCPOCF₃ 5 IX 3CCGUF 4 IX 2CCPUF 4

EXAMPLE 11

TABLE 12 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3CDUQKF 13 Δn 0.097 I 2APUQKF 10 Δε 12.8 I 3APUQKF 5 Cp 89 I 3PUQKF 10 γ1 67 II 3CCV 42 K₁₁ 12.9 III VCCP1 6 K₂₂ 6.5 IX 3CCGUF 5 K₃₃ 15.0 IX 2CCPUF 5 IX 3CCPUF 4

EXAMPLE 12

TABLE 13 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3CCQKF 15 Δn 0.100 I 3GUQKF 5 Δε +8.7 I 3APUQKF 9 Cp 100 I 3PGUQKF 5 γ1 80 II 3CCV 34 K₁₁ 13.6 II 3CCV1 2 K₂₂ 6.9 III VCCP1 2 K₃₃ 17.0 IV 3CCUF 9 IV 3CCPOCF₃ 5 VIII 3CPPC3 3 IX 3CCGUF 5 IX 3CPGUOCF₃ 6

EXAMPLE 13

TABLE 14 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3CPPQKF 3 Δn 0.122 II 3CCV 50 Δε +2.4 II 3CCV1 9 Cp 75 VI 2PGUF 11 γ1 46 VII 1PGP2V 6 K₁₁ 12.2 VII 2PGP2V 8 K₂₂ 6.1 VII V2PGP1 13 K₃₃ 12.8

EXAMPLE 14

TABLE 15 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3PUQKF 9 Δn 0.116 II 3CCV 38 Δε +5.2 II 3CCV1 10 Cp 75 III VCCP1 3 γ1 46 III V2CCP1 9 K₁₁ 12.5 VI 2PGUF 8 K₂₂ 6.3 VI 3PGUF 9 K₃₃ 12.8 VII 2PGP3 5 VII 2PGP4 5 VIII 3CPPC3 4

EXAMPLE 15

TABLE 16 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 2APUQKF 10 Δn 0.101 I 3PUQKF 15 Δε +9.3 I 3APUQKF 2 Cp 80 II 3CCV 42 γ1 54 III VCCP1 9 K₁₁ 10.9 IV 3CCPOCF₃ 10 K₂₂ 5.5 IX 3PPGUF 2 K₃₃ 15.0 IX 3CPGUOCF₃ 10

EXAMPLE 16

TABLE 17 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3PUQKF 8 Δn 0.100 II 3CCV 27 Δε +6.3 II 3CCV1 5 Cp 90 III VCCP1 13 γ1 68 III V2CCP1 11 K₁₁ 12.2 IV VCCGF 6 K₂₂ 6.1 IV 3CCUF 4 K₃₃ 16.0 V 3CPUF 9 V 3CGUF 7 VI 2PGUF 3 IX 3CCGUF 7

EXAMPLE 17

TABLE 18 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3PUQKF 15 Δn 0.100 II 3CCV 32 Δε +6.3 III 3CCP1 7 Cp 90 III 3CCP2 6 γ1 71 III 3CCP3 3 K₁₁ 13.5 III 3CPP2 3 K₂₂ 6.8 IV 2CCGF 6 K₃₃ 16.0 IV 3CCGF 10 V 3CPGF 6 IX 2CCPUF 4 IX 3CCPUF 4 IX 4CCPUF 4

EXAMPLE 18

TABLE 19 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3PUQKF 15 Δn 0.100 II 3CCV 32 Δε +6.2 III VCCP1 10 Cp 90 III V2CCP1 6 γ1 68 III VCPP3 3 K₁₁ 13.2 IV VCCGF 6 K₂₂ 6.6 IV 3CCPOCF₃ 10 K₃₃ 15.8 V 3CPGF 6 IX 2CCPUF 4 IX 3CCPUF 4 IX 4CCPUF 4

EXAMPLE 19

TABLE 20 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 2APUQKF 5.5 Δn 0.098 I 3PGUQKF 6 Δε +2.6 II 3CCV1 12 Cp 81 II 5PP1 6 γ1 51 II 3CCV 43 K₁₁ 13.8 III VCCP1 11 K₂₂ 6.9 III V2CCP1 7 K₃₃ 15.4 III VCPP3 3.5 VII 2PGPF 6

EXAMPLE 20

TABLE 21 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3PGUQKF 4 Δn 0.099 I 3PUQKF 16 Δε +7.8 II 3CCV 33 Cp 91 II 3CCV1 3 γ1 70 II 5PP1 5 K₁₁ 12.5 III 3CCP1 6 K₂₂ 6.3 IV 2CCGF 6 K₃₃ 17.5 IV 3CCGF 9 IV 3CCPOCF₃ 6 IX 2CCPUF 4 IX 3CCPUF 4 IX 4CCPUF 4

EXAMPLE 21

TABLE 22 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3PGUQKF 12 Δn 0.101 I 3PGUQKF 4 Δε +5.8 II 3CCV 34 Cp 91 II 3CCV1 5 γ1 62 II 5PP1 7 K₁₁ 13.7 III 3CPP2 6 K₂₂ 6.9 III VCCP1 3 K₃₃ 16.8 III 3CCP1 6 IV 3CCPOCF₃ 7 IV 3CCGF 8 IX 3CCPGF 4 IX 3CCPGOCF₃ 4

EXAMPLE 22

TABLE 23 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 2APUQKF 6 Δn 0.098 I 3PGUQKF 6 Δε +2.6 II 3CCV1 12 Cp 80 II 5PP1 8 γ1 51 II 3CCV 43 K₁₁ 13.8 III VCCP1 9 K₂₂ 6.9 III V2CCP1 7 K₃₃ 15.4 III VCPP3 3 III 3CPP2 6

EXAMPLE 23

TABLE 24 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3PGUQKF 7.5 Δn 0.098 II 3CCV 42 Δε +2.6 II 3CCV1 10 Cp 80 II 5PP1 7 γ1 51 III VCCP1 13 K₁₁ 13.6 III V2CCP1 12 K₂₂ 6.8 VII 2PGPF 7 K₃₃ 16.0 VII 3PGPF 1.5

EXAMPLE 24

TABLE 25 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3PGUQKF 7.5 Δn 0.098 II 3CCV 40 Δε +2.6 II 3CCV1 11 Cp 81 II 5PP1 8 γ1 50 III VCCP1 14 K₁₁ 14.2 III V2CCP1 7 K₂₂ 7.1 III 3CCP1 5 K₃₃ 15.7 VII 2PGPF 7.5

EXAMPLE 25

TABLE 26 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Types Compound codes weight parameters values I 3PGUQKF 4 Δn 0.102 I 3PUQKF 10 Δε +5.8 I 2APUQKF 5 Cp 90 II 3CCV 40 γ1 64 II 3CCV1 5 K₁₁ 13.5 III VCCP1 12 K₂₂ 6.8 III 3CPP2 5 K₃₃ 16.7 III 3CCP1 4 IV 3CCPOCF₃ 4 VII 2PGPF 5 IX 3CCPGF 3 IX 5CCPGF 3

COMPARATIVE EXAMPLE 1

As compared with methyl-free compounds, the compounds of type I provided by the present invention have a mutual solubility with an improvement of 30% or greater. The experimental method is a conventional method for low temperature observation and implementation: adding same in percentage by mass into a host LC, and pouring into a liquid crystal cell at −40° C., and the specific results thereof can be found in the following table:

TABLE 27 Low temperature mutual solubility comparison Addi- tion propor- Host tions LC 3APUQUF 3APUQKF 3PGUQUF 3PGUQKF OK 10 OK OK NG OK 15 NG OK OK 20 OK NG

As compared with methyl-free single crystals, the single crystal provided by the invention still maintains a good low temperature mutual solubility when the added mass is 5% more, and it can be seen therefrom that the single crystal of type I provided by the present invention has an excellent low temperature mutual solubility and can effectively improve the low temperature stability of the liquid crystal composition.

COMPARATIVE EXAMPLE 2

TABLE 28 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Compound codes weight (%) parameters values 2PGP3 4 Δn 0.097 3CCV 43 Δε +2.5 3CCV1 12 Cp 78 5PP1 4 γ1 53 2PGUF 6 K₁₁ 13.8 3PGUF 5 K₂₂ 6.9 VCCP1 11 K₃₃ 14.6 V2CCP1 10 3CPGUOCF₃ 5

The values of the performance parameters of the liquid crystal compositions obtained in example 1 and comparative example 1 are summarized and compared, and reference can be made to table 29.

TABLE 29 Comparison of performance parameters of liquid crystal compositions Δn Δε Cp γ1 K₁₁ K₂₂ K₃₃ Example 1 0.098 +2.6 81 50 13.9 7.0 15.6 Comparative 0.097 +2.5 78 53 13.8 6.9 14.6 example 1

Upon comparison, it can be seen that, as compared with comparative example 1, the liquid crystal composition provided in example 1 has a low rotational viscosity, i.e. having a faster response time.

COMPARATIVE EXAMPLE 3

TABLE 30 Percentages by weight of each component and performance parameters of the liquid crystal composition Percentages by Performance Parameter Compound codes weight (%) parameters values 3PUQUF 7 Δn 0.100 3CUQUF 7 Δε +5.6 2PGUF 7 Cp 90 3CCV 35 γ1 90 3CCV1 8 K₁₁ 12.8 VCCP1 10 K₂₂ 6.5 V2CCP1 6 K₃₃ 16.2 2PGP3 4 2CCPUF 5 3CCPUF 5 3CPPC3 4 3CGPC3 2

The values of the performance parameters of the liquid crystal compositions obtained in example 5 and comparative example 2 are summarized and compared, and reference can be made to table 31.

TABLE 31 Comparison of performance parameters of liquid crystal compositions Δn Δε Cp γ1 K₁₁ K₂₂ K₃₃ Example 5 0.101 +5.8 91 62 13.8 6.9 17.1 Comparative 0.100 +5.6 90 90 12.8 6.5 16.2 example 2

Upon comparison, it can be seen that, as compared with comparative example 2, the liquid crystal composition provided in example 5 has a large elastic constant and a low rotational viscosity, and therefore has a shorter response time and a faster response speed.

It can be seen from the above examples that the liquid crystal composition provided by the present invention simultaneously contains a compound containing 2-methyl-3,4,5-trifluorobenzene linked to a difluoromethoxy bridge bond and a non-polar bicyclic compound, has a low viscosity, high resistivity, suitable optical anisotropy, large elastic constant and excellent light stability and thermal stability, and can reduce the response time of the liquid crystal display, thereby solving the problem of a slow response speed of the liquid crystal display. Therefore, the liquid crystal composition provided by the present invention is suitable for fast-response TN, IPS and FFS-type TFT liquid crystal display devices, is particularly suitable for IPS and FFS liquid crystal display devices, and is especially suitable for quick-response liquid crystal display devices.

Although the present invention has been described in detail with general explanations and specific embodiments, it is obvious to a person skilled in the art that some modifications or improvements can be made thereto based on the present invention. Therefore, all these modifications and improvements which can be made without departing from the scope of the present invention belong to the scope claimed in the invention.

INDUSTRIAL APPLICABILITY

The present invention provides a liquid crystal composition, which liquid crystal composition simultaneously contains a compound containing 2-methyl-3,4,5-trifluorobenzene linked to a difluoromethoxy bridge bond and a non-polar bicyclic compound, has a low viscosity, high resistivity, suitable optical anisotropy, large elastic constant and excellent light stability and thermal stability, and can reduce the response time of the liquid crystal display, thereby solving the problem of a slow response speed of the liquid crystal display. Therefore, the liquid crystal composition provided by the present invention is suitable for fast-response TN, IPS and FFS-type TFT liquid crystal display devices, is particularly suitable for IPS and FFS liquid crystal display devices, and is especially suitable for quick-response liquid crystal display devices, and has broad application prospects and a good industrial applicability in the liquid crystal display field. 

1. A liquid crystal composition containing a 2-methyl-3,4,5-trifluorobenzene liquid crystal compound, comprising, in percentages by weight, 1-50% of one or more compounds represented by general formula I and 10-70% of one or more compounds represented by general formula II,

wherein R₁, R₂ and R₃ each independently represent a C₁-C₁₂ linear alkyl group or a C₁-C₁₂ linear alkyl group having one or more non-adjacent CH₂ substituted with O, S or CH═CH; n each independently represents 0 or 1; A₁, A₂ and A₃ each independently represent the following structures:

and A₄ and A₅ each independently represent a trans-1,4-cyclohexylene group or a 1,4-phenylene group.
 2. The liquid crystal composition according to claim 1, comprising, in percentages by weight, 3-20% of one or more compounds represented by general formula I, and 17-63% of one or more compounds represented by general formula II; or comprising 21-45% of one or more compounds represented by general formula I, and 20-45% of one or more compounds represented by general formula II.
 3. The liquid crystal composition according to claim 1, further comprising 0-30% by weight of one or more compounds represented by general formula III,

wherein R₄ and R₅ each independently represent a C₁-C₁₂ linear alkyl group or a C₁-C₁₂ linear alkyl group having one or more non-adjacent CH₂ substituted with O, S or CH═CH; and A₆ each independently represents the following structures:


4. The liquid crystal composition according to claim 3, wherein the amount of the one or more compounds represented by general formula III is 10-26% by weight.
 5. The liquid crystal composition according to claim 1, further comprising 6-45% by weight of one or more compounds represented by general formulas IV to IX,

wherein R₆ and R₉ each independently represent a C₁-C₁₂ linear alkyl group or a C₁-C₁₂ linear alkyl group having one or more non-adjacent CH₂ substituted with CH═CH; R₇, R₈ and R₁₀-R₁₂ each independently represent a C₁-C₁₂ linear alkyl group; L₁-L₈ each independently represent H or F; X₁-X₃ and X₅ each independently represent F, CF₃, OCF₂H or OCF₃; X₄ each independently represents F, CF₃, OCF₃, and a C₁-C₅ linear alkyl group or a C₂-C₅ linear alkenyl group; and A₇ and A₈ are each independently selected from the following structures:


6. The liquid crystal composition according to claim 5, wherein the amount of the one or more compounds represented by general formulas IV to IX is 28-37%.
 7. The liquid crystal composition according to claim 5, comprising, in percentages by weight, 6-39% of one or more compounds represented by general formula I, 22-62% of one or more compounds represented by general formula II, 2-26% of one or more compounds represented by general formula III, and 6-44% of one or more compounds represented by general formulas IV to IX.
 8. The liquid crystal composition according to claim 1, wherein the compound represented by general formula I is selected from one or more of the compounds represented by formulas I-A to I-U:

and the compound represented by general formula II is selected from one or more of the following compounds:

wherein R₁ each independently represents a C₁-C₇ linear alkyl group; R₂ each independently represents a C₁-C₇ linear alkyl group or linear alkoxy group or a C₂-C₇ linear alkenyl group; and R₃ each independently represents a C₁-C₇ linear alkyl group.
 9. The liquid crystal composition according to claim 1, wherein the compound represented by general formula I is selected from one or more of the compounds represented by formulas I-A-1 to I-U-4:

preferably, the compound represented by general formula II is selected from one or more of the compounds represented by formulas II-A-1 to II-C-24:

preferably, the compound represented by general formula III is selected from one or more of the structures of formulas III-A-1 to III-C-30:

preferably, the compounds of general formulas IV to IX are selected from one or more of the following structures:

wherein R₆ each independently represents a C₂-C₇ linear alkyl group or linear alkenyl group; R₇, R₈ and R₁₀-R₁₂ each independently represent a C₂-C₇ linear alkyl group; R₉ and R_(x) each independently represent a C₁-C₇ linear alkyl group or a C₂-C₇ linear alkenyl group; more preferably, R₆ each independently represents a C₂-C₅ linear alkyl group or linear alkenyl group; R₇, R₈ and R₁₀-R₁₂ each independently represent a C₂-C₅ linear alkyl group; and R₉ and R_(x) each independently represent a C₁-C₅ linear alkyl group or a C₂-C0 ₅ linear alkenyl group.
 10. The use of the liquid crystal composition of claim 1 in TN, IPS and FFS mode liquid crystal displays 